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Abstract

Background

During the 2009 H1N1 influenza pandemic, Australian public health officials closed
schools as a strategy to mitigate the spread of the infection. This article examines
school communities’ understanding of, and participation in, school closures and the
beliefs and values which underpinned school responses to the closures.

Methods

We interviewed four school principals, 25 staff, 14 parents and 13 students in five
schools in one Australian city which were either fully or partially closed during
the 2009 H1N1 pandemic.

Results

Drawing on Thompson et al’s ethical framework for pandemic planning, we show that
considerable variation existed between and within schools in their attention to ethical
processes and values. In all schools, health officials and school leaders were strongly
committed to providing high quality care for members of the school community. There
was variation in the extent to which information was shared openly and transparently,
the degree to which school community members considered themselves participants in
decision-making, and the responsiveness of decision-makers to the changing situation.
Reservations were expressed about the need for closures and quarantine and there was
a lack of understanding of the rationale for the closures. All schools displayed a
strong duty of care toward those in need, although school communities had a broader
view of care than that of the public health officials. Similarly, there was a clear
understanding of and commitment to protect the public from harm and to demonstrate
responsible stewardship.

Conclusions

We conclude that school closures during an influenza pandemic represent both a challenge
for public health officials and a litmus test for the level of trust in public officials,
government and the school as institution. In our study, trust was the foundation upon
which effective responses to the school closure were built. Trust relations within
the school were the basis on which different values and beliefs were used to develop
and justify the practices and strategies in response to the pandemic.

Keywords:

Background

The 2009 outbreak of influenza A (H1N1) highlighted the substantial risk to health
and security posed by pandemic influenza. Public health measures such as social distancing,
school closures, home isolation, use of stock-piled anti-viral drugs and provision
of H1N1 vaccine were important components of local, national and international responses
to the pandemic. Pre-2009, pandemic planning had acknowledged the need to understand
community values, beliefs and expectations if these measures were to be successfully
implemented [1-3]. Yet, surprisingly little research has been conducted post-2009, to understand the
experience and perspectives of those affected by implementation of such measures [4,5]. Research into the beliefs and values which underpinned community responses during
the pandemic is crucial to enhance planning for future pandemics and other public
health emergencies.

One domain in which community beliefs and values might be expected to be particularly
important is school closures. School closures were a key non-pharmacological public
health measure used to limit pandemic influenza transmission during the 2009 H1N1
Pandemic [6]. School closures are expected to slow viral transmission by limiting contact between
school children, as children are thought to be particularly susceptible to influenza
and highly infectious [7]. The success of the strategy relies on adherence to recommendations for home isolation
and other behavioural change.

School closures pose practical and policy challenges. They transmit powerful messages
to those affected, and the wider community, about the severity of the pandemic and
the likely risk it poses [8]. Modelling studies [9,10] and natural experiments [11,12] suggest that school closures are only effective if invoked early, before sustained
community transmission occurs. Therefore, a decision to close a school must be made
under considerable uncertainty and, because information about virulence of a viral
strain only becomes available during the course of the pandemic, recommendations about
the need for school closures are likely to change as the pandemic progresses.

In our study we focused on school closures as a micro-instance of the impact of restrictive
public health measures on the community. The aims of our study were to examine the
implementation of school closures as a strategy to manage a local outbreak of a pandemic
strain of influenza particularly:

• school communities’ understanding of, and participation in the closures;

• interactions between the school community and health officials; and

• the beliefs and values which underpinned community responses.

School communities in this context relates to staff, students and parents who go to
or work within the school environment.

Methods

Recruitment and study procedure

Our study took place in one Australian city. All seven schools which had closed or
partially closed during the pandemic were invited to participate in the study. In
schools with whole school closures, students, parents and staff from the year level
of the index case student and two or three other year levels were invited to participate.
In schools with partial closures, students, families and staff in affected year levels
were invited to participate. Administrative support staff such as librarians and reception
staff from all schools were also invited to participate.

We included all participants who consented to be interviewed until we reached data
saturation for each participant type. Data saturation occurred at the point at which
no more new information was observed in the data for each participant type (school
staff, parents and students). Semi-structured interviews were conducted by one of
two researchers (JC or RT) between October 2009 and April 2010. Participants were
asked to reflect on the impact of school closures on students and teachers and their
families, precautionary measures undertaken, communication and the appropriateness
of school closures and overall government response. Interviews were digitally recorded
and transcribed and analysis undertaken using NVivo8 software [13].

Study participants

Four non-government schools (one senior high school and three kindergarten-year 12
schools) and one government high school agreed to participate. We interviewed the
school principal in all five schools, but one school elected not to have interviews
with the school community due to time considerations. We interviewed 25 staff (excluding
school principals), 14 parents, and 13 students from October 2009 to April 2010. The
spread of staff, students and parents was mostly consistent across the schools, although
more staff than parents and students were interviewed in all schools. Students ranged
in age from 12 to 17 years and nine of the parents and students were parent-student
pairs (these students and their parents were interviewed separately). Interviews typically
ranged between 15–30 minutes for students, 20–40 mins for parents and teachers and
60 minutes for principals.

Data analysis

Using thematic analysis as outlined in Braun & Clarke [14], one researcher (JC) generated initial content codes based on the topic of the conversation.
For example ‘what happened when the school closed’, and ‘what were you required to
do’, and ‘what did you actually do’ were content codes that related to the pandemic
experience and participants’ responses [15]. A second researcher (RT) independently repeated the coding. Coding differences were
resolved through discussion and thematic codes emerged based on the data and initial
content codes. The codes were further refined in discussion with the whole study team.
Further analysis used the lens of the ethical framework for pandemic planning proposed
by Thompson et al. [1]. Framing the analysis in this way gave rise to conceptual codes such as trust, duty
of care, reciprocity and protecting the public.

Thompson’s framework was developed “…to inform decision-making…[and] encourage reflection
on important values, discussion and review of ethical concerns arising from a public
health crisis” [1]. The framework is divided into five ethical processes, based on Daniels’ widely used
“accountability for reasonableness” model [16] and ten ethical values identified from previous research and expert consultation.
The processes are intended to support deliberative decision-making with the expectation
that such deliberation will enhance the acceptability of actions that may need to
be taken in a pandemic. The ethical values provide guidance for actual decisions;
when there is tension between values, ethical processes can provide mechanisms to
secure resolution. Overall, the framework is intended to work alongside the overarching
goals of pandemic planning – to minimise morbidity, mortality and social disruption
[17]. We have chosen to use the Thompson framework because it builds on and is consistent
with other ethical frameworks, such as Carter et al. [18], Selgelid [19], Viens et al. [20] and WHO [21], but is more inclusive in terms of its categories (Table 1).

The study was approved by the Children, Youth and Women’s Health Service Human Research
Ethics Committee and the Department of Education, South Australia. All participants
and/or parents gave written informed consent before participation.

Results

Schools’ responses to closure

Schools complied with public health advice and requests, sometimes at great inconvenience.
The unprecedented nature of the event, and the schools’ limited prior experience of
anything similar, meant that they relied heavily on instruction from public health
officials, whose efforts, for the most part, were praised. Schools were generally
happy to accept advice from public health officials about when and how to close their
schools.

Initial procedures instituted by schools at the outset of the closure were often based
on generic ‘school emergency’ plans and, given the lack of prior experience, principals
suggested that they had to “make things up” with guidance from government officials.
Participants also indicated that the Health Department did not provide specific plans
for school closures.

“Well we have a generic plan for those sort of things......, and we swung that plan
into action.....But that’s more of a disaster plan and this really in a sense wasn’t
disaster but it was an issue that had to be managed and contained… on an ongoing rolling
basis…” [Principal, School 3]

Schools used their existing information dissemination practices, some to better effect
than others. Two schools with whole school closures communicated relevant information
directly through a whole school assembly. In another school, the media became aware
that the school would be closing, before the principal, staff and students were informed.
This caused considerable confusion: many parents called the school (some from overseas)
after seeing media reports and before they were alerted by the school. Some students
attended school while others did not. This confusion posed great difficulty for the
principal of this particular school:

“So we were left then to split our attention three ways: we had to deal with the students
who hadn’t heard the media reports and came to school anyway, and we dealt with those
in exactly the same way as the whole student body had the media not been alerted before
us. Then we had to deal with another tranche of students who did get the media and
stayed at home and rang in and the switchboard went into meltdown. And then we dealt
with the last contingent which was the media scrum on the front door”. [Principal,
School 1]

Some schools used email and websites to ensure students particularly final year students,
continued with schoolwork and had access to teachers during the quarantine period.

“I think it was done well. We were the first school, luckily for us we are already
an on-line school. I worked at another school for 12 months while I was here, I don’t
know how they would have done it because there was no student-teacher email” [Teacher,
School 1]

Interactions between schools and public health officials

The amount of interaction with public health officials varied across the stages of
the pandemic but was highest in schools with whole school closures. Officials attended
school closure announcements and were available to answer specific staff and student
questions. Students and staff involved in whole school closures were also contacted
by public health officials during their seven day quarantine to make sure they were
adhering to the guidelines and their antiviral medication course and to address questions
and concerns. With a few exceptions, the interactions were positive.

“we trusted fully with the Department of Health. They inspired a lot of confidence.
Again, I think they were fantastic with this, and I was able to ring them and say,
look, I’m struggling with this” [Principal, School 5]

Participants suggested this level of support was not available for partial closures.
School principals indicated public health officials were available to them via telephone
to assist but were less available to students, parents and other staff.

Personal responses during the closures

How individuals in school communities responded was frequently dependent on the extent
and nature of the information they received and how they interpreted that information.
While school principals could contact public health officials, many parents, teachers
and students relied on information provided by the school or through the media.

“And it wasn’t that the school said, come back to school, but I then made the decision,
well if it’s been lifted and it’s on the radio…” [Parent, School 2]

Most people in the school communities adhered to quarantine but few believed that
there was a severe risk. In the absence of clear instructions many invented their
own rules according to their own criteria. This was predicated on their understanding
of what constituted visible symptoms, the acceptable degree of contact (or lack thereof)
with those who were infected, and the risk of becoming infected or infecting others.

The lack of clear instruction resulted in a range of practices. Some people stayed
at home for the full seven days, had friends leave supplies on the doorstep and did
not leave the house. A second group thought the school closures might be an overreaction
but attempted to comply. This group adhered to quarantine for several days but, when
they remained symptom-free, decided that it was safe to resume some activities such
as a trips “to the shops or taking the dog for a walk”. Some parents, to avoid being
seen as irresponsible, quarantined their children. However, whether the children complied
with this directive is unclear as most students were home alone. One student met friends
regularly although his parents believed that he remained at home. A third group saw
the closure as an ineffective overreaction. This group did not quarantine other than
not coming to school.

Very few people were extremely concerned that they might become infected or transmit
the virus to others. Those who were most concerned were pregnant women, and those
with young children.

“But he said, look, I just want to let you know because you’ve got - your partner’s
pregnant and it might not be good for you to come in. But we are having a briefing
as well, and explained that the Year 10s would be getting the Tamiflu and their teachers
should be as well. So when I asked who the student was, and I was told it was a Year
10 student of mine that I had quite a lot of contact with over those last two days.
So I spoke to my partner about it and we decided that I would go in to find out exactly
what was going on, and to collect that medication, and then I would talk to her as
to what we’d do. But, you know, basically we’d agreed that she and - I’ve got a two
- two-and-a-bit year old son, they would move out for a week”. [Teacher, School 1]

Staff at some schools maintained close contact via email and phone and as a group
determined that they were safe to re-enter the community before the quarantine period
was completed. This was based, in part, on rumours circulating through these informal
staff cliques that other staff members (including the principal) were already out
in the community.

“Yeah. Yeah. We were all, you know, sort of either emailing or talking to each other
going, well what do you think? No one’s sick. Right, okay. Reckon it’s safe? We still
tried to minimise. It’s not like we’d go to massive sporting events or…” [Teacher,
School 3]

In summary, the school closures exhibited several features which made the situation
particularly challenging: there was clearly urgency, but no clear response plan; there
was considerable uncertainty, both about disease severity and of the correct response;
recommendations for the imposition, continuation and lifting of closures and home
isolation changed rapidly; and the key sources of authoritative information for students,
families and staff were school leadership teams, who were not infectious disease experts.

Making meaning of school closures in a pandemic: ethical processes and values for
schools, parents, students and policy makers

To build an effective response to a pandemic in the future, we will need to understand
not only what school communities are likely to do but also why they respond in certain ways. Using the framework of Thompson et al. [1], we examined the ethical processes and values employed in the school communities’
responses to school closure. The framework has two parts: the first focuses on ethical
processes and the second on underpinning values. Both components are important. Ethical
processes can lend legitimacy to actions during a pandemic, so that stakeholders are
more able to accept the difficult decisions that may need to be made. However, as
Thompson et al. [1] noted, “ethical processes do not guarantee ethical outcomes” and their framework
therefore also has “ten key ethical values to guide decision-making that address substantive
ethical dimensions of decision-making in this context”.

Overall, we found that there was considerable variation between and within schools
in their attention to ethical processes and values. Schools varied in the extent to
which information was shared openly and transparently, the degree to which school
community members considered themselves participants in decision-making and their
thoughts about the responsiveness of decision-makers to the changing situation. In
all schools there were reservations about the need for closures and quarantine and
a lack of understanding of the rationale for the closures. However, in all of the
schools, members of the school communities could articulate core values such as providing
care to all affected by the pandemic, protecting the public from harm and promoting
wise use of resources. To some degree in each school, coordination and cohesion between
public health officials and community members and the protection of privacy, equity
and liberty were also acknowledged and valued. In contrast, all the schools struggled
with the notions of proportionality and reciprocity. In the following sections we
discuss the ethical processes (Table 2) and values (Table 3) apparent in the descriptions provided by our participants.

Ethical processes and the practices adopted during the school closures

Accountability, openness & transparency

According to the Thompson framework (see Table 2), transparency is essential for building and maintaining public trust in public health
decisions and displaying accountability. Although all schools demonstrated competence
and familiarity with communication strategies, not all communication was open and
transparent. Much of the confusion, frustration and lack of adherence with home quarantine
and other measures associated with the school closure stemmed from a perception amongst
some members of school communities that health officials and government were not being
transparent. In particular, some participants believed information about the severity
of the pandemic and virulence of the virus was withheld.

Inclusiveness

Thompson et al. stated that ethical decision-making should be made with stakeholder
views in mind and stakeholders should be included in decision-making. In our study,
there is some evidence that this was accomplished effectively, with the school and
health department staff working closely together to shape the information for families
and its timing and format. One school also worked with student groups to enhance the
quality of the information transmitted via social media.

However, stakeholders were not always included in the decision-making processes, at
a whole school or individual level. In these cases, the messages that were transmitted
about home quarantine and school closures seemed to be poorly understood. In particular,
the lack of specific guidelines for the range of situations which presented exacerbated
confusion for families.

Reasonableness

The government’s failure to adequately convey a clear rationale for the measures undertaken
tended to reduce the credibility of information and led to widespread misinterpretation
of the advice about home isolation. Misunderstanding was exacerbated when the ways
in which the closures were effected seemed to be at odds with the advice being given
(see Table 2). Taken together with the rapidly changing situation, these factors led students,
parents and teachers to construct their own rationales and act according to their
own assessment of what they should do.

Responsiveness

Ethical decision-making requires that decisions be revisited and revised as new information
emerges. The rapidly changing instructions about school closures, from a policy of
whole school closures, to partial school closures, to no school closures within a
month, could certainly be seen as responsive. However, it is clear that the school
communities had difficulty understanding these changes and felt that their views and
interpretations were not always taken into account. The government and public health
officials failed to flag in advance that changes were likely to occur and, as changes
happened, failed to adequately explain why the changes were required. Thus, rather
than being responsive, some members of school communities interpreted the policy shifts
as inconsistent and as evidence of lack of interest in their views.

Ethical values important during the school closures

The ethical values that were articulated by the members of these school communities
(see Table 3) can be separated into four groups: values which were strongly in evidence in all
settings (the duty to provide care, protection of the public from harm and stewardship);
values which were adopted but variably expressed (solidarity, privacy, equity and
individual liberty); values for which there was little evidence or contrary evidence
(proportionality and reciprocity) and a final value, trust, which played a foundational
role underpinning other values.

Values which were strongly in evidence

Duty to provide care

Health officials and school leadership teams all had a strong commitment to provide
high quality care for the members of the school community, although, they were driven
by slightly different professional understandings of that duty. Health officials appeared
to be working towards the accepted public health goals of minimising morbidity and
mortality while using the least restrictive measures available to slow the spread
of the infection. Schools on the other hand, had a broader notion of duty of care:
they wanted to ensure the welfare of the whole school community and, at the same time,
provide quality teaching and learning for students. Schools were willing to work closely
and collaboratively with public health officials to ensure that they were adhering
to the recommendations (to fulfil their broad obligations to protect the school community)
and they needed, at the same time, to consider the educational impact on students.

Protection of the public from harm

Clearly, the need to protect the public from harm is at the core of the pandemic mitigation
strategies. Many teachers, parents and students clearly understood this and also appreciated
the need to maintaining a balance between protecting the public from the spread of
H1N1 and ensuring that the school closures did not cause other unintended harms.

Stewardship

Schools, and some teachers in particular, were acutely aware of the possible disruption
to the learning of final year high school students and they went to significant lengths
to minimise this, even when teachers were themselves in home isolation. In addition,
some schools took the opportunity to use the pandemic for other educational goals,
including reinforcing hygiene practices such as hand washing, sneeze etiquette, and
cleaning of surfaces, or focusing on pandemic literacy generally.

Values for which evidence was mixed

Solidarity

There was a more mixed commitment to the value of solidarity. Where schools and public
health officials worked closely together to ensure that school communities had adequate
information, there was a strong sense of shared purpose. Personal contact with public
health officials seemed to engender the strongest feeling of a collaborative effort
to mitigate the effects of the pandemic. Personal contact also increased individual
parents’ and students’ confidence in management of the closure.

However, when personal contact between health department staff and participants was
more limited, this appeared to reduce the sense of working together to combat the
pandemic. Solidarity was also undermined when different rules appeared to apply to
different members of the school community.

Privacy

Schools were acutely aware of the need to try to protect the privacy of affected students.
However, their efforts were hampered by rapid spread of information via social media
and a significant amount of media coverage. The way information was conveyed in some
schools also undermined privacy: in one school, all students were handed a note giving
information about the closures; however, students who were required to adopt home
isolation (because they may have been in contact with the student diagnosed with H1N1)
were given a note in a different colour, clearly identifying them to other students
and staff.

Equity

Equity (or the lack of it) was an important issue, but school communities felt they
could do very little about it. For example, access to the internet was assumed, but
limited, for some students and parents, and public health officials also were not
prepared for the provision of information in languages other than English, or to suit
varying degrees of health and general literacy. Some schools filled this gap with
their own processes for managing language difficulties.

Individual liberty

Balancing restrictions on individual liberty with the need to protect the public from
harm was a key challenge in managing the pandemic. It was clear among those affected
by the school closures that some valued their individual liberty more highly than
others, and this was reflected in their response to the closures, in particular their
lack of acceptance of the need for home isolation.

Values for which there was little evidence or contrary evidence

Proportionality

Most members of school communities felt that the response required of them was disproportionate
to the danger posed to the community by the pandemic. This perception may have developed
in hindsight (which our participants had). However, the lack of transparency about
the rationale for actions and the rapid changes in the advice provided, without additional
explanation about those changes, undermined the sense that the school closure would
be effective in limiting the spread of disease.

Reciprocity

“Reciprocity not only requires that individuals should not be overly burdened by measures
to protect public health, but also that individuals are supported in a way that allows
them to fulfil their obligations” [20]. Some of our interviewees thought that the adverse impact of home isolation on them
had not been taken into account. We also found that some level of stigmatisation was
experienced by the initially affected student in each school and subsequently by the
student’s class or year level. Sometimes the stigmatisation contained implicitly racist
elements.

Key value: trust

Thompson et al. place ‘trust’ at the end of their list of key ethical values. This
is a good positioning from the perspective of the findings of our study, as trust
was a key ethical value underpinning the responses, practices, and strategies used
during the school closures. Where closures happened effectively and smoothly, members
of the school community appeared to trust that the closure strategy was important
to the health of the nation and would be effective in slowing the spread of the influenza
virus [22]. They also trusted that complying with the advice of the government to close schools
was in the best interests of the school community [21].

Discussion

Despite similar challenges, there was considerable variation between and within schools
in the ways in which ethical processes and values were enacted and interpreted. With
respect to processes, accountability, openness and transparency, and inclusiveness were apparent in some schools, but not so clearly in others. All schools displayed
a degree of responsiveness to the changing situation, but some members of school communities interpreted the
policy and procedure shifts as inconsistent and unresponsive to local circumstances.
Finally, participants across all schools thought that the ways in which the closures
were managed failed the reasonableness test. In general, the government’s failure to adequately convey a clear rationale
for the measures they were taking gave an impression that decisions were not being
based on good reasons.

With respect to values, the picture was even more complex. All schools displayed a
strong awareness of their duty of care toward their students, although members of the school communities had a broader view
of care than that of the public health officials. Similarly, there was a clear understanding
of and commitment to protect the public from harm and to demonstrate responsible stewardship.

There was a more mixed commitment to the values of solidarity, liberty, privacy and equity. While there were clearly shared aims and cohesion between public health officials
and schools in some situations, this solidarity was undermined by lack of clear information
and differences in interpretations of restrictions on movements by various members
of the school communities. Similarly, although all schools were generally aware of
privacy and equity issues, practices instituted in haste without the benefit of forward
planning, acted to undermine these values.

Finally, in accordance with their understanding of the unreasonableness of the closures,
most members of school communities considered that the response of closing the schools
was in no way proportional to the danger posed to the community. They also thought that insufficient attention
had been paid to reciprocity. Little account appeared to have been taken of the impact of quarantine on individuals
or the stigmatization that was attached to being labelled as a ‘case’.

Underlying all of these values and processes was the value of trust. Trust was the foundation upon which effective responses to the school closure were
built. Trust relations were the basis on which different values and beliefs were used
to develop and subsequently, to justify the practices and strategies that were undertaken.
Simplistically put, a school closure seemed to work well when there were high levels
of trust between all players. In an environment of trust, the school community could
put in place processes that were ethical and which were an expression of the school’s
underlying values. An environment of trust turned the pandemic into an opportune learning
experience. This was well expressed by one of the principals:

Look in some respects, yes, our students weren’t there for a week, but I think what
we learnt as a community from this far outweighed what the [students] would learn
in a week from that. I thought they learnt a lot about the Human Swine Flu, about
a lot of things from this, about resiliency and about community, about compassion.
So, you know, they’re our four strategic values, we’ve got faith, excellence, community,
compassion. I think we learnt something about all those four areas. (Principal, School
5)

The extent to which public health officials are able to harness the existing trust
relationships between school communities and their school as an institution may itself
depend on the stability and endurance of those relations and the school’s efficacy
in managing its day to day business [23]. Thus, in schools where trust relations are already fractured or weak, or where the
day-to-day business of managing the school is problematic, public health emergency
managers could not rely on those trust relations to build trust with the community
indirectly. In other words, if trust within the school community is already low, then
it cannot be used as a resource to mobilise community adherence with the school closure
strategy, and in fact may be a barrier to action.

Conclusions

The findings reported in this study concerning both what schools did, and the values
which underpinned their actions, are important for understanding broader community
responses to a pandemic and preparing for future infectious disease outbreaks. There
are, of course, limitations inherent in this study. It was undertaken in one Australian
city; thus, to some degree, relations between school communities and public health
officials reflect the quite specific circumstances of this city. In addition, not
all opinions will have been captured in the limited sample size, but we believe our
sampling strategy enabled a broad group of views to be included. Different environments
and disease experiences are likely to influence findings.

Nonetheless, it is clear from our findings that school closures during an influenza
pandemic represent both a challenge for public health officials and a litmus test
for the level of trust in public officials and government. During a public health
emergency, schools that are closed act as agents of public health emergency managers.
Schools therefore have a significant role to play in the public health response to
an infectious disease outbreak.

Competing interests

The authors declare that they have no competing interests.

Authors’ contributions

ABM contributed to the design of the research and to the interpretation of data. ABM
also substantially contributed to later drafts of this manuscript. RT contributed
substantially to the coordination, collection, analysis and interpretation of the
data. RT also contributed substantially to drafting this manuscript. JEC contributed
to the collection of data and initial analysis and interpretation of the data. JEC
also contributed to initial drafts of this manuscript and revision of later drafts.
JMS contributed to the interpretation of data, the drafting of the manuscript and
critical revision of it. HM conceptualised and designed this research and is the Principal
Investigator on the NHMRC grant that funded it. HM also contributed to the interpretation
of the data and drafting the manuscript. HM has approved the manuscript in its current
form for publication. All authors have approved the final version of the manuscript
for publication.

Acknowledgments

This work was supported by the National Health and Medical Research Council [Grant
Number 626867].